ChikaraDev has a number of useful tutorials and sample applications, most of which you can right-click and select View Source:
But if you really want to learn Flex well, and embed nuggets of knowledge about Flex deep within your mind, you should just go through the Flex Builder help system from the top (but not the API pages). I went through 3/5 of the Flex Builder help sys twice each time I prepared for (and passed) the Flex 2 and Flex 3 with AIR ACE (Adobe Certified Expert) exams.
The Flex Builder help system is simply awesome (though admittedly it is not perfect)!
If this post answers your question or helps, please mark it as such.
Flex Development and Support Services